How can you make a scratched metal procedurally?
If we take a Voronoi Texture set to Distance to Edge, and do a Math -&gt; Less Than operation we get this map:

We can use another Voronoi Texture set to F1 to generate a map that lets us subtract out most of the corners.

Note that we are using the same scale for both Voronoi Textures, and we are clamping the Math -&gt; Subtract operation to prevent our values from falling below 0.

The Less Than threshold controls the thickness of scratches, the Greater Than threshold controls how much of the initial map we remove.
You can stack up as many layers of this as you want:

And then plug it into a Bump node with distance set to -1 to sink it into the mesh instead of pushing out.

Here's a setup attempting to resemble your reference image.